# Metastatic Renal Cell Carcinoma Presenting a Maxillary Mucosal Lesion as a First Visible Sign of Disease: A Case Report and Review of Literature

## TL;DR

A rare case of kidney cancer first showing up as a mouth lesion highlights the need for careful diagnosis of unusual oral swellings.

## Contribution

This case report presents a rare instance where metastatic renal cell carcinoma first appeared as an oral lesion, emphasizing diagnostic considerations.

## Key findings

- The oral lesion was the first visible sign of metastatic renal clear-cell carcinoma.
- Histopathological and immunohistochemical analyses confirmed the renal origin of the lesion.
- Additional metastases were found in the adrenal gland, lungs, and bone.

## Abstract

Background and Clinical Significance: Renal cell carcinoma (RCC) is the third most common cancer that metastasizes to the oral and maxillofacial region following breast and lung cancers. Metastatic involvement in the oral cavity is rare and can present as a diagnostic challenge due to non-specific clinical features that mimic other benign or malignant conditions. The limited information available regarding oral metastasis of RCC highlights the importance of recognizing this uncommon presentation. Case Presentation: A 50-year-old female presented with a painful swelling in the buccal and palatal mucosa of the right maxilla that progressively enlarged over several months. Initially, this lesion was diagnosed clinically as a pyogenic granuloma. However, given the lesion’s continued growth and unusual presentation, a biopsy was performed. Histopathological examination confirmed the lesion as metastatic renal clear-cell carcinoma (ccRCC), with immunohistochemical analysis verifying the renal origin. Further diagnostic tests, including a computed tomography (CT) urogram, chest CT, and bone scintigraphy, revealed additional metastases in the left adrenal gland, lungs, and bone. Conclusions: This case is notable because the oral lesion was the first visible sign of RCC, making it a rare presentation of metastatic RCC. This underscores the importance of thorough history taking, detailed clinical evaluations, and considering rare metastatic conditions in the differential diagnosis of oral swellings. Additionally, this case reinforces the significance of routine cancer screenings for early detection of undiagnosed cancer. We also updated a previous literature review of metastatic RCC to the head and neck region, covering cases until 2023.